Communication system



F. $.KINKEAD ET AL COMMUNICATION SYSTEM Filed- April 19, 1933 2Sheets-Sheet 2 E s. KIN/(E140 T. L. CORW/N lNVE/V TORS SUB. SET

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A TTOR/VE Y Patented Dec. 17, 1935 umrso S'iT rATENT OFFICECOMMUNICATION SYSTEM Application April 19, 1933, Serial No. 666,828

1 Clain'l.

This invention relates to that type of communication system in which asubscribers station is provided with dual service in the form of twocommunication lines connected thereto, one line being for one type ofservice, such as leased wire service, and the other line being foranother type of service, such as exchange service. I

Heretofore in a communication system, if a subscriber wished to besupplied with two different types of service, he was forced to equip hisstation with a separate set of station apparatus for each type ofservice. This duplication of apparatus is objectionable from a coststandpoint as it is practically double the cost of one set of stationapparatus, This duplication is also undesirable from the'viewpoint ofspace considerations because the extra apparatus takes up space whichcould be used for other purposes. Another objection is found in the costof maintaining' and operating two sets of station apparatus.

All of these objections are done away with by means of the presentinvention, the objectv of which is to supply dual service over eitheropen or closed loops to a subscribers station having only one set ofstation apparatus.

Another object of this invention is to provide switching apparatus at asubscribers station (provided with dual service) for quickly switchingits station apparatus from transmission and/or reception over onecommunication line totransmission and/or reception over anothercommunication line.

Still another object of this invention is to enable a calling station togive a non-continuous audible signal and a continuous visible signal to'an operator at a subscribers station provided description will be setforth with reference to V the drawings in which: 7 r

Fig. 1 represents a subscribers station having only one set of stationapparatus is conopen loop'to another station I02.

'run under these conditions.

nected by a normally open loop to another station;

Fig. 2 represents a somewhat similar subscribers station but which isprovided with dual service over normally open loops;

Fig. 3-'represents a subscribers station having only oneset of stationapparatus which is connected by a normally closed loop to anotherstation; and V Fig. 4 represents a somewhat similar subscribers stationbut which is provided with dual service over normally closed loops.

Ordinary service over a normally open loop As has been stated above,Fig. 1 shows a subscribers station IIII- which has only one set of'station apparatus (teletypewriter and associated apparatus) and which isconnected by a normally The loop is rendered normally open'by means ofdouble pole double throw switch I03 which is normally in its openposition as is shown in Fig. 1. When in this open position, the leftpo-rtion'of switch I03 opens the loop so that current from station I 02would go to station 1 0| and then pass through line relay I04, sendingcontacts I05, break key I06, and then through switch I03 to ground.Station I02 may be either a single subscriber's station, like stationl0l, or it may be a central ofiice, such as the central office disclosedin Patexit 1,804,548 granted May 12, 1931 to G. S. Vernam. If it is asingle subscribers station, it

. may have station apparatus similar to that of station 10!.

' The right portion of switch I03 opens a path from the source of powersupply I01 through motor generator I08 and motor I38 of the subscribersprinting telegraph set. Since, under these conditions motor generatorI08 will not be operated, it will not supply energizing current 40 toprinter magnet I09. Also, motor I38 will not The transmission orreception of signal impulses by station IIll can not now take placebecause of the fact that neither printer magnet I09 nor motor I38 isenergized.

For the transmission or reception of signal impulses, switch I03 is putin its closed position which is opposite to that shown in'Fig. l. The

cordingly be closed. Likewise, the path from power supply I01 throughmotor generator I08 armature of line relay I04 and energize printer 3magnet I00. When line relay I04 is now successively energized anddeenergized in response to the transmission or reception of signalimpulses, its armature will successively open and close therebysuccessively opening and closing the energizing circuit for printermagnet I00.

If station I02 is a single subscribers station, it may be said thatstation I02 and station I0! are provided with leased wire service. Ifstation I02 is a central oflice, then it should be stated that station'IOI is provided with exchange service. With the arrangement shown inFig. 1, if the subscriber at station IOI wishes to be supplied with dualservice, that is, with both leased wire and exchange service, it isnecessary for him to equip station IOI with a separate set of stationapparatus for each type of service. As has been stated above, thisduplication of apparatus is objectionable for several reasons.

Dual service over normally open loops However, by means of the specialswitching arrangement of this invention, a subscriber's station havingonly one set of station apparatus may be provided with dual service overnormally open loops as is shown in Fig. 2 where subscribers station Billis connected by means of normally open loops to station 202 and station2| 0. It may be assumed for the purpose of illustration that station 202is a central olfice, such as the central oflice disclosed in Patent1,804,548 granted May 12, 1931 to G. S. Vernam, and that station 2 I0 isa single subscribers station.

The station apparatus (teletypewriter and associated apparatus) atstation 20I is rendered normally non-operated by means of double poledouble throw switch 203 which is normally in its open position as isshown in Fig. 2. While in this open position, the right port-ion ofswitch 203 opens a path from the source of power supply 201 throughmotor generator 208 and motor 230 of the subscribers printing telegraphset. Since motor generator 208 is not operated now, it will not supplyenergizing current to printer magnet 209. Also, under these conditionsmotor 238 can not run. As was the case with station IOI under similarconditions, the transmission or reception of signal impulses by station20I can not now take place because of the fact that neither printermagnet 209 nor motor 2-38 is energized.

The left portion of switch 203 opens the subscribers loop to centraloflice 202 and provides current from central oilice 202 with three pathsto station 20L The first path leads from central ofiice 202 to station20I by passing through an upper left pair of contacts of key switch 2II, down through line relay 204, sending contacts 205, break key 206,through middle and bottom left sets of contacts of key switch 2H, andfinally through switch 203 to ground. The second path leads from centralofiice 202 to station 20!, through ringer 2 I2, through the bottom leftset of contacts of key switch ZII, and then through switch 203 toground. The third path is similar to the second path-except that,instead of passing through ringer 2I2, current will pass through relay2I3.

If an operator at central oflice 202 wishes to communicate with thesubscriber at station 20!, the operator momentarily impresses apreassigned ringing voltage on the line. This ringing voltage willfollow the second and third paths described above. By following thesecond path, the ring-v ing voltage will cause the operation of an alarmdevice (ringer 2I2) Since ringer ZIZ is operated only during the timeringing voltage is impressed upon the line, a non-continuous audiblesignal will be given to the subscriber at station 20 I. By following thethird path, the ringing voltage will operate relay 2I3. The operation ofrelay 2E3 closes a path for current from power supply 202' to passthrough switch 203, through both another alarm device (signal lamp 214)and relay 7H5, through the armature of relay 2 I3, and then back topower supply 25?. As soon as relay EH5 opcrates, current from powersupply 201 will pass through its armature and lock relay 2I5. This willcause continuous operation of the second alarm device (signal lamp 2M)thereby giving a continuous visible signal to the subscriber. Therefore,calling apparatus (ringer 2 i 2 and lamp 2M) at subscribers station 2%!is capable of being actuated by another station, such as central ofiice292, for informing subscribers station 2e! that it desires attention.

If the subscriber at station 20 i' wishes to answer a call from centralofiice 282, he closes switch 203. The right portion of switch 203 opensthe path through relay 2I5 and lamp 2M thereby extinguishing lamp 254and releasing relay 2I5. At the same time, a path is closed from powersupply 201 through motor 238 and motor generator 208. This will energizeprinter magnet 209. The left portion of switch closes a path for currentfrom central ofiice 202 to pass through the subscribers line relay 20 asdescribed above but, instead of passing through switch 203 to ground,the current will now pass back to central ofiice 2G2. Transmission orreception of signal impulses may now take place between subscribersstation 20I and central oflice 202.

If the subscriber at station 2H3 wishes to communicate with thesubscriber at station 20I, he momentarily closes the loop leading fromstation 2i0 to station 20L This enables current to pass through relay2H5 and energize it. When station 20! is connectedto central office 202,the line current is applied at central office 202, but when station 20iis connected to station 2 I 0 one of them must apply line current. Forthe sake of simplicity, it may be assumed that it is applied at station2 Hi. When relay 2 I0 operates, its armature closes a path for currentfrom power supply 201 to pass through and operate an alarm device(ringer 2 I1). Also, a path is closed through the armature of relay 2!.8 through both relay 2 i8 and another alarm device (signal lamp 2 I9)and then back to power supply 207. When relay 2%?! operates, itsarmature closes a locking-up circuit leading from power supply 20?through the top right set of contacts of switch 2! I, the armature ofrelay 2I8, through both relay 2| 8 and alarm device Bit, and. then backto power supply 20?. When relay 2H3 releases, ringer 2!! will becomeunoperated but, due to the locking-up circuit, lamp 2I0 will remain lit.This procedure gives a non-continuous audible signal and a continuousvisible signal to the subscriber at station 20!. Therefore, callingapparatus (ringer ZI I and lamp 2I0) at subscribers station EDI iscapable of being actuated by another station, such as subscribersstation ZIQ, for informing subscribers station 20l that it desiresattention.

It is to be understood that the invention is not to be limited to theparticular kinds of alarm devices described above. Ringers 222 and 2Hand signal lamps 2H, and 259 could be interchanged if desired therebygiving the subscriber a noncontinuous visible signal and a continuousaudible signal. Also, any other type of alarm device of the difference.

could-be substituted for ringers'2 I 2 and .211 and/ or signal lamps 2Mand .2l9.

If the subscriber at station 26! wishes to answer a call from thesubscriber at station 2 l 0,-he closes switch 293 and operates switch 2to the left which is the position opposite to that shown on thedrawings. As has been described above,.the right portion of switch 203closes a path from power'supply 2B7 through motor238-and motor generator238 thereby energizing printer magnet 299. When switch 2! I is put intoposition at the left, the top right set of contactsrof switch 2 willopen thereby opening the locking-up path from power supply 291 throughlamp 219. This will extinguish lamp 2 I9. At the same time, the

path from subscribers station 2H) through relay H6 will be opened by thetop left set of contacts.

of switch 2| I; The path from central office 202 through the subscribersline relay 204 will now be changed so as to lead from central office 202through the middle left sets of contacts of switch 2 down through thebottom left sets of contacts of switch 2H to ground. In the path forringing current from central ofiice 202, the ground connected to thelower left set of contacts of switch 2 l I will now be substituted forthe ground associated with switch 283. The path will now be closed forcurrent from subscriber's station 2H) to pass through the middle rightset of contacts of switch 2H, down and around through break key 205,"sending contacts 285, line relay 204, upper left set of contacts ofswitch 2| I, and then back to stationZ l9. Transmission or reception ofsignal impulses may now take place between subscribersstations 23! and2H3;

The current used for communication between stations Ziil and subscribersstation 2 I!) may not always be equal to the current used forcommunication between station Zlil and central ofiice 202; To take careof any difference between these two currents, a biasing circuit isprovided for line relay 204. For the'sake of illustration, let it besupposed that, the current in the loop leading to central ofiice 232 isless than the current in the loop leading to subscribers-station.2H1.Let it also be assumed that the amount of the difference between thesetwo currents is known and that resistance 22!! compensates for theamount. Now, when switch 2| I is in the position shown in the drawings,resistance 228 will reduce the biasing current from motor generator 208.When switch 2| l is in the opposite position to that shown in thedrawings, resistance 225i will be sho-rt-circuited out of the biasingcircuit thereby increasing the biasing current.

Ordinary service over a. normally closed loop then through special delaykey 339, break key 306,]

sending contacts 335, line relay 3G4, and back over the loop to station332. Station 392 may be either a-single subscribers station like station30L orit may be a central .ofiice, such as the central office disclosedin Patent 1,804,548 granted May 12, 1931- to G.-S-. Vernam. If it is'asingle subscriberszstation, it may have station apparatus similarto thatof station 38!.-

' When no signal impulses are being transmitted or received at station3i! l, power switch 303 is kept .in. its .open position, as is shown inthe drawings.

In. this open position, switch 303 opens a path from the source of'power supply 301 through motorgenerator 303 and motor 338 of thesubscribers printing. telegraph set.. Since under these conditions motorgenerator 308'will not be operated, it will not supply energizingcurrent to printer magnet 309. Also, under these conditions motor 338can not run. The transmission or reception ofsignal impulses by-station3M can not now take place because of the fact that 1 neither printermagnet 369 nor motor 338 is en- 7 ergized.

For the transmission or reception of signal impulses, switch 303 is putin its closed position which is opposite to that shown in Fig. 3. The 1path from power supply 307 through motor generator 308 and motor 338will now be closed. Currentfrom motor generator 388 may now pass throughthe armature of line relay 3% and energize printer :magnet 399. Whenlinerelay 304 2 is now successively energized and deenergized inresponse to the transmission or reception of signal impulses, itsarmature will successively open and close thereby successively openingand closing'the energizing circuit for printer magnet 369. A dis- 2connect signal may be given by the subscriber at stationiiill byoperating the special delay key 339 which causes a long break signal tobe transmitted. Key 330 is so arranged that that portion oi the loopwhich is at station 30! will be held 3 closed during the transmission ofthe long break signal.

As was the casev with the arrangement shown in Fig. 1, if the subscriberat station 3% wishes to be supplied with dual service, that is, withboth 3 leased wire and exchange service, it is necessary for him toequip station 33! with a separate set of station apparatus for each typeof service. As has been stated above, this duplication of apparatus isobjectionable for several reasons. 4

Dual service over normally closedloops However, bymeans of the specialswitching arrangement of this invention, a subscribers station havingonly one set of station apparatus (teletype- 4:

writer and associated apparatus) may be provided with dual service. overnormally closed loops as is shown'in Fig. 4. In Fig. 4, subscribersstation to: is connected by means of normally closed loops to stations4B2 and ilil. It may be assumed for the 5 purpose of illustration thatstation 462 is a central ofiice, such as the central ofiice disclosed inPatent 1,804,548 granted May 12, 1931 to G. S. Vernam, and that stationMil is a single subscribers station. According to this assumption,station Mil is now provided with dual service comprising exchangeservice to central office 402' and leased wire service tosubscribers'station s l 9. Under the normal conditions shown in Fig. 4,current from central office 462 passesover the loop to station 43 I,then through special delay key 438, through relay M3, through a middleleft set of contacts of key switch 4H to break key 3%, sendingcontactsfibjline relay eats, up through another middle left set of contacts ofswitch 4! i, 6 and'then back'over the loop to central office 432. At thesame time, the loop leading to subscribers station 4! 3 isshort-circuited by the top left set of contacts-of switch 4! l. Undernormal conditions,

path from power supply tillthrough motor generator 433 and motor .38 isopened by reason of switch 133 being in its open position.

If an operator at central office' 432 wishes to communicate with thesubscriber at station dill, 7

the operator momentarily opens the loop to station 40|. The opening ofthe subscribers loop will cause relay M3 to release. The top contact ofrelay 4|3 will now close a path to operate an alarm device (buzzer 4|2).This path leads from power supply 401, the top armature of relay 4|3,through buzzer 4|2, the armature of buzzer M2, the bottom left set ofcontacts of switch 4| the left portion of switch 403, and then back topower supply 401. However, buzzer 4|2 will operate when current passesthrough it and its armature will be drawn away from its contact therebyopening the path just described. When this path opens, buzzer 4 I2 willrelease and its armature will fall back thereby closing the circuit andcausing this procedure to be repeated during the time that relay 4 l3remains unoperated. The effect of this action is the generation of abuzzing sound by the armature of buzzer 4|2.

At the same time, the bottom armature of relay 4 I3 will close a path tooperate another alarm device (signal lamp 4|4). This path leads frompower supply 401, through the right portion of switch 403, through bothlamp M4 and relay M5, the bottom armature of relay M3, and then back topower supply 401. This will light lamp 4 4 and will cause the operationof relay 4|5 which will result in its armature closing a locking-upcircuit for relay 4|5.

When the operator at central oflice 402 closes the loop to subscribersstation 40| relay 4 I3 will be operated again. The top armature of relay4 3 will open the path to buzzer 4 I 2 thereby causing it to ceaseoperating. However, since relay 4|5 is provided with a locking-upcircuit, lamp 4|4 will remain lit. In summary, it may be stated thatcalling apparatus (buzzer 4| 2 and lamp M4) at subscribers station 40|is capable of being actuaated by another station, such as central oiflce402, for informing subscribers station 40| that it desires attention bygiving a non-continuous audible signal and a continuous visible signalto the subscriber at station 40|.

It is to be understood that this invention is not to be limited to theparticular kinds of alarm devices described above. Buzzer M2 and signallamp 4|4 could be interchanged if desired thereby giving the subscribera non-continuous visible signal and a continuous audible signal. Also,any other type of alarm device could be substituted for buzzer 4|2and/or signal lamp 4|4.

If the subscriber at station 40| wishes to answer a call from centraloffice 402, he closes switch 403. The right portion of switch 403 opensthe path through lamp 4| 4 thereby extinguishing it. At the same time, apath is closed from power supply 401 through motor 438 and motorgenerator 408. This will energize printer magnet 409. The left portionof switch 403 opens the path from power supply 401 to buzzer 4 l2.Transmission or reception of signal impulses may now take place betweensubscribers station 40| and central ofiice 402.

If the subscriber at station 40| wishes to extinguish lamp 4M withoutholding communication with central ofiice 402, he could do so bymomentarily operating switch 403 to its closed position. The momentaryclosure of switch 403 would open the path from power supply 401 to lamp4|4. This would cause relay 4 l5 to release thereby opening itslocking-up circuit.

If the subscriber at station 40| wishes to communicate with subscriberat station 4 I0, he closes switch 403 and operates switch 4| to the leftwhich is the position opposite to that shown in the drawings. As hasbeen described above, the right portion of switch 403 closes a path frompower supply 401 through motor 438 and motor generator 408 therebyenergizing printer magnet 409. When switch 4| is put into the positionat the left, the top left set of contacts of switch 4|| will openthereby removing the short-circuit across the loop to subscribersstation 4|0. Current from central ofiice 402 is now provided with a pathover the loop to subscribers station 40|, through special delay key 430,through relay M3, the middle sets of contacts of switch 4| and then backover the loop to central ofiice 402. Buzzer 4 2 is provided with a pathfrom power supply 401 through the armature of relay 4|3 (when relay 4 |3has released), through buzzer 4| 2, the armature of buzzer 4|2, thelower set of contacts of switch 4| and then back to power supply 401.This enables central ofiice 402 to signal the subscriber at station 40|by means of buzzer 4| 2.

Current from subscribers station M0 is now provided with a path over theloop to station 40| through the right set of contacts of switch 4| I,break key 406, sending contacts 405, line relay 404, the upper left setof contacts of switch 4| and then back over the loop to station 4|0.Transmission or reception of signal impulses may now take place betweensubscribers stations 40| and 4H].

For the sake of simplicity, no alarm device has been shown at station40| which can be operated by the subscriber at station 4|0. If desired,such calling apparatus may be added to the station apparatus at station40| in a manner similar to that in which it was added to the stationapparatus of station shown in Fig. 2. Also, for the sake of simplicity,it has been assumed that the current used for communication betweenstation 40| and subscribers station M0 is equal to the current used forcommunication between station 40| and central oiiice 402. If thereshould be any difference between these two currents, a biasing circuitcould be provided for line relay 404 which would be essentially the sameas the biasing circuit provided for line relay 204 shown in Fig. 2.Also, station 4| 0 could be connected to station by means of a normallyopen loop if desired.

Stations 20| and 40| have been shown to be supplied with dual service;If it were desired to supply them with multiple service of severaldifferent types by means of a plurality of transmission lines connectedto a plurality of difierent stations, this could readily be done in amanner similar to that shown in the drawings. In fact, it is to beunderstood that the arrangements shown in the drawings and describedabove are illustrative of the operation of the invention and will serveto assist in interpreting the claim.

The claim is not to be restricted to the precise construction describedabove, but is intended to include all changes and modificationsemploying the principles and features of operation of the invention. 5

What is claimed is:

In a, printing telegraph system, a subscribers printing telegraphstation supplied with multiple service in the form of a plurality oftransmission lines connected thereto for communication with a pluralityof different printing telegraph stations connected to the transmissionlines, the transmission lines being for different types of service withline current of diiferent amounts,

7 said subscribers printing telegraph station having only one printingtelegraph set for the transmission and reception of messages over thetransmission lines, and switching apparatus for switching the printingtelegraph set from operation over one transmission line to operationover another transmission line; said printing telegraph set includingonly one line relay, a biasing circuit for enabling the line relay tooperate correctly with current of any amount that is used lines inaccordance with the amount of current I in the particular transmissionline which is being used for communication purposes at a given time.

FULLERTONS. KINKEAD. THOMAS L. CORWIN.

